Re: [MW:27227] Why high stress developed in P_91 materials

comment by c c girotra

The p91 grade materail is high cr amd mo alloyed steel and these elements cause air hardeing and by corollary also increase tensile strength  hence stresses are bound to be there. It is 90,000psi class material.CR and Mo help resist oxidation resistance at high temp and creep resistance.

Plain carbon steel has no alloying/ no air hardening material and has uts of 60,000 to 70,000 psi only.(42kg/mm2--52kg/mm2)

CCGirotra 

On Friday, November 3, 2017 at 3:54:53 PM UTC+5:30, gerr...@yahoo.com wrote:

Thermal expansion of P91 steel is higher than carbon steel and one of the reason for increased stresses.

Thermal conductivity of P91 steel is lesser than Carbon steel and may be reason for slow cooling.

Normally, P91 steel will of Higher Thickness than Carbon steel and that will be one of the reasons for Higher stresses.

Microstructure will be Martensite after welding and which will be further Tempered to obtain Tempered Martensite.

Thanks & Regards

J.Gerald Jayakumar

0091-9344954677

On Friday, November 3, 2017, 7:06:57 AM GMT+4, 'Rajesh Kasvala' via Materials & Welding <material...@googlegroups.com> wrote:

Dear Expert 

Please tell me why high  stress developed  in P_91 materials then carbon steel, 

Metallurgical point of view, what is changes in structure. 

Regard 

Rajesh 

Sent from Yahoo Mail on Android

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